Geochemical assessment of some natural waters from eastern and south-eastern Macedonia

285 Geologica Macedonica, Vol. 29, No. 1, pp. 5–14 (2015)

GEOME 2 In print: ISSN 0352 – 1206

Manuscript received: March 10, 2015 On line: ISSN 1857 – 8586

Accepted: April 13, 2015 UDC: 556.3:550.42(497.73/.74)

Original scientific paper

GEOCHEMICAL ASSESSMENT OF SOME NATURAL WATERS

FROM EASTERN AND SOUTH-EASTERN MACEDONIA

Tena Šijakova-Ivanova1_{, Vesna Ambarkova}2

1_{Faculty of Natural and Technical Sciences, “Goce Delčev” University,} P.O. Box 201, MK 2000 Štip, Republic of Macedonia

2_{Faculty of Dentistry, Department of Preventive and Pediatric Dentistry,} “Ss. Cyril and Methodius” University in Skopje,

Vodnjanska 17, MK-1000 Skopje, Republic of Macedonia

tena.ivanova@ugd.edu.mk

A b s t r a c t: The paper deals with short review and determination of macro-, micro-, trace and ultratrace ele-ments in some natural waters from еastern and сouth-eastern Macedonia. In our study were investigated 16 samples of natural waters from the villages Trabotivište near the city of Delčevo, Istibanja near Kočani, Neokazi near Pro-bištip, Plačkovica, Karaorman, Gorni Balvan and Lakavica near Štip, Jargulica near Radoviš, Murtino, Robovo, Gab-rovo and Smolare near Strumica. Obtained results showed that most of the analyzed elements in all selected water samples were below the Macedonian maximum allowable levels and WHO water standards. Increased concentrations of some elements indicate anthropogenic pollution of the water from the fertilization of arable land, livestock farms. There is a strong positive correlation between Ca → SO4, Na, Mg; Ti → Ca, Mg, Na, K, B; U → Mo, Rb, Cs, As; B

→ Ca, Ti, Ge, Cl, HCO3; Li → Mg, Na, K, B, Sr, Rb; Ge → Ca, Mg, Na, B, Ti, Li, Cl, Pb; Cl → Mg, Na, K, B, Sr, Li, Pb; HCO3 → Ca, Mg, Na, K, B, Ti, Sr, Li, Pb, Co, Se, Ge; NO3 → Na, Sr, Li, Pb, Cs, Se; SO4 → Na; TDS → EC. According to the obtained values for total hardness, investigated waters are hard, moderately hard and very hard. High values for total hardnes sare mainly due to solubility of carbonate rocks. Positive CAI values noted in Neokazi (samples 1 and 2), Jargulica (samples 1 and 2), Novo Selo, Murtino, Robovo, Gabrovo and Smolare suggest that so-dium and potassium from water are exchanged with magnesium and calcium in rock following base exchange reac-tions (chloro-alkaline equilibrium), whereas negative CAI values noted at Trabotivište, Istibanja, Karaorman Plač k-ovica, Lakavica (samples 1 and 2) suggest that magnesium and calcium from water are exchanged with sodium and potassium in rocks favouring cation-anion exchange reactions (chloro-alkaline disequilibrium). After Piper diagram the type of water in the study area is mainly calcium/magnesium bicarbonate and are most likely result of the compo-sition of the geological environment through which the water flows where this natural water circulates. Knowing the natural water quality of the research area is of particular importance because these waters are used by the residents of this region as drinking water and for irrigation.

Key words: natural water; trace elements; pH; TDS

INTRODUCTION

Water is important source of intake of trace elements in humans and an essential component for life. The chemical constituents of natural water are derived from water–rock interactions such as dissolution and mineral–water equilibria. Thus, the geochemistry of a natural water sample reflects a some times complex history of its flow path thro-ugh various rock types under varying physioche-mical conditions, temperature and pressure.

All waters contain both natural contaminants, particularly inorganic contaminants that arise from the geological formations through which the water flows and to a varying extent, anthropogenic pollu-tion by microorganisms and chemicals. In natural

waters, trace elements, especially metals, may be present in different physico-chemical forms vary-ing in size, charge and density. Trace elements in natural water comprehensively covers the micro-chemical processes occurring in the water phase.

Trace elements can be categorized into those es-sential to human life, such as Fe, Cu, Mn, Cr, Co, Mo, Se, Zn and those potentially toxic like Ag, As, Cd, Pb and Ni. Certain essential trace elements such as Cr, Fe, Co, Mn and Se can be toxic when concentrations are raised above specific levels.

Trace elements concentrations in the natural waters vary widely depending on the geochemistry of rocks in the immediate environment.

Interac-tions of water with rocks and soils developed from them, dictate our intake of these elements. They are mostly associated with igneous and metamor-phic rocks and in particular, with ore bodies (Ed-wards et al., 2000).

Trace elements needed in very minute quanti-ties (Selinus, et al., 2005) may have biotoxic ef-fects in human biochemistry and are of great con-cern.

Knowledge of rock types and mineralization in a particular area can help to find out potential health problem with concentration of particular

elements and the type of trace elements contamina-tes varies with the mineralization of the area (Pyenson, 2002, Williamson and Rimstidt, 1994).

In our study were investigated samples of natural waters from the villages: Trabotivište near the city of Delčevo, Istibanja near Kočani, Neokazi near Probištip, Plačkovica, Karaorman, Gorni Balvan and Lakavica near Štip, Jargulica near Radoviš, Murtino, Robovo, Gabrovo and Smolare near Strumica. Localities where samples are taken are shown in Figure 1.

Fig. 1. Localities where samples are taken

RESULTS AND DISCUSSION According to quantity, elements in natural

waters are devided on:

– macro (majority) elements: >100 mg/kg (ppm) = 0.01% Na, K, Mg, Ca, Cl, P,

– micro (minority) elements: 10 – 100 mg/kg Fe, Zn,

– trace elements: < 10 mg/kg Al, As, B, Cd, Co, Cr, Cu, F, Hg, I, Mn, Mo, Ni, Pb, Se, Sn,

– ultratrace elements: <1 µg/kg (ppb).

There are several factors that control how much of a certain trace element will be present in natural waters: amount of the element in the rock through which the water flows; solubility of that element under the conditions that exist in the aqui-fer; flow rate of the water and hence the contact time between the water and the rock (Hem, J. D., 1989).

The presence of macro-, micro-, trace and ul-tra-trace elements in investigated water samples have been depicted in tables 1, 2, 3, 4, respectively.

T a b l e 1

Concentration of Ca, Mg, Na, K, Fe, Mn, Al, B, Mo and Ti

Ca Mg Na K Fe Mn Al B Mo Ti

Trabotivište (Delčevo) 59 16.61 13.80 3.4 33.20 0.397 0.099 24 0.75 73 Istibanja (Kočani) 29 18.65 26.98 14.3 31.52 0.091 0.091 46 0.74 35 Neokazi – sample 1 (Probištip) 60 35.10 51.80 5.4 19.13 0.080 0.053 88 5.12 84 Neokazi – sample 2 (Probištip) 56 29.82 52.10 11.4 23.90 0.082 0.037 100 5.59 79 Gorni Balvan (Štip) 36 26.70 69.60 3.8 18.51 0.064 0.050 63 11.90 51 Plačkovica (Štip) 13 3.19 5.11 1.5 16.14 0.061 0.044 3 0.07 16 Karaorman (Štip) 26 102.60 114.50 19.6 28.55 0.079 0.448 173 0.83 39 Lakavica – sample 1 (Štip) 117 119.10 69.30 7.6 19.57 0.076 0.048 73 1.95 171 Lakavica – sample 2 (Štip) 124 106.80 104.30 5.4 21.99 0.115 0.197 385 0.64 181 Jargulica – sample 1 (Radoviš) 30 13.33 12.22 3.2 20.28 0.091 0.084 24 0.30 39 Jargulica – sample 2 (Radoviš) 35 14.84 17.02 4.0 23.24 0.085 0.088 55 0.34 47 Novo Selo (Strumica) 19 4.90 7.25 2.3 23.46 0.068 0.057 5 0.54 22 Murtino (Strumica) 21 8.98 10.00 1.6 26.44 0.719 0.051 43 0.68 24 Robovo (Strumica) 24 10.66 10.00 1.2 26.60 0.188 0.050 38 2.05 28 Gabrovo (Strumica) 25 3.65 6.73 1.7 25.69 0.087 0.149 2 11.66 29 Smolare (Strumica) 16 5.45 4.23 4.4 25.72 0.283 0.068 2 1.71 18

T a b l e 2

Concentration of Sr, Ba, Rb, Li, Cs, Be, Zn, Pb, Cd, Cu and Ni

Sr Ba Rb Li Cs Be Zn Pb Cd Cu Ni Trabotivište (Delčevo) 234 0.19 0.99 3.4 0.077 0.002 34.21 0.117 0.032 3.72 1.23

Istibanja (Kočani) 262 9 1.18 6.6 0.046 0.004 8.12 0.240 0.010 2.55 0.61

Neokazi – sample 1 (Probištip) 2228 9 14.70 27.3 7.274 0.021 7.19 0.689 0.028 1.03 1.03 Neokazi – sample 2 (Probištip) 2758 34 15.75 31.0 12.31 0.009 6.59 0.529 0.018 1.16 1.04

Gorni Balvan (Štip) 311 6 0.83 21.6 0.042 0.016 5.18 0.398 0.023 1.14 0.62

Plačkovica (Štip) 63 6 0.29 2.4 0.059 0.008 49.39 0.074 0.011 0.58 1.42

Karaorman (Štip) 639 3 1.54 32.9 0.094 0.013 10.24 0.536 0.011 1.61 0.63

Lakavica – sample 1 (Štip) 814 30 0.85 9.4 0.052 0.023 18.03 0.579 0.012 1.11 2.26

Lakavica – sample 2 (Štip) 992 6 0.41 17.8 0.023 0.015 18.04 0.798 0.017 1.75 2.51

Jargulica – sample 1 (Radoviš) 660 5 0.11 1.5 0.074 0.009 3.46 0.246 0.009 1.37 0.62

Jargulica – sample 2 (Radoviš) 192 27 0.26 2.7 0.076 0.007 2.24 0.187 0.008 0.56 0.74

Novo Selo (Strumica) 60 3 0.19 5.2 0.072 0.003 24.41 0.075 0.011 1.27 0.51

Murtino (Strumica) 302 35 0.27 1.2 0.058 0.002 1.04 0.108 0.009 0.95 0.33

Robovo (Strumica) 356 36 0.18 1.8 0.049 0.003 2.42 0.178 0.015 0.83 0.34

Gabrovo (Strumica) 24 1 0.45 1.4 0.076 0.003 6.54 0.058 0.026 0.66 0.43

Calcium and magnesium

The contents of Ca2+ _{and Mg}2+ _{determine the}

hardness of the water, which is an important parameter for reducing the toxic effects of some of the elements. Concentration of calcium in studied waters is in range of 13–124 ppm.

Source of magnesium includes ferromagne-sium minerals in igneous and metamorphic rocks and magnesium carbonate in limestone and dolo-mite. Magnesium salts are more soluble than cal-cium, but they are less abundant in geological for-mations. Concentration of magnesium in studied waters varies from 3.19 to 119.10 ppm.

Sodium

The major source of sodium in natural waters is from weathering of feldspars, evaporates, and clay. Sodium salts are very soluble and remain in solution. Concentration of sodium in studied wa-ters varyies from 5.11 to 114.50 ppm. Typical so-dium concentrations in natural waters range be-tween 5 and 50 mg/l. The most common sources of elevated sodium levels in natural water are: erosion of salt deposits and sodium bearing rock minerals, naturally occurring brackish water of some aqui-fers, infiltration of surface water contaminated by road salt, irrigation and precipitation leaching through soils high in sodium, natural water pollu-tion by sewage effluent, infiltrapollu-tion of leachate from landfills or industrial sites.

Potassium

Potassium is less abundant than sodium in natural waters. Its concentration rarely exceeds 10 mg/l in natural waters. The range of specific levels of sodium is minimum 1.2 ppm in Robovo to maximum 19.6 ppm in Karaorman. In all tested waters, the sodium content is lower than the WHO standard.

Iron

Iron in the ferric form is nearly insoluble in normal water, but in the ferrous form 10 ppm or more may be present. In natural waters, iron may be present as ferrous bicarbonate (Fe(HCO3)2),

fer-rous hydroxide, ferfer-rous sulfate (FeSO4), and

or-ganic (chelated) iron. Concentration of iron in studied waters varies from 16.14 to 33.20 ppb.

Manganese

Manganese is rarer in water than iron in range from 0.043 to 0.0868 ppb except in Novo Lagovo

where the value of the Mn is equal to 5.623 ppb. Manganese may be brought into solution by activ-ity of microorganisms.

Aluminium

Aluminum is nearly insoluble in water in the pH range from 5 to 9. Concentration of aluminium in studied waters varies from 0.037 to 0.197 ppb.

Boron

Concentrations of boron in natural water throughout the world range widely, from 0.3 to 100 mg/l. Boron is a component of some very stable minerals and in trace concentrations is widespread in soils and waters.

The main minerals of B are borax (sodium tetraborate, Na2B4O7·10H2O) and kernite

(Na2B4O7·4H2O). Borax and kernite are fairly

soluble in water: the solubility of those minerals in 20°C water reaches 25 g/kg (Крайнов et al., 2004). Na2B4O7 + 7H2O = 4H3BO3 + 2NaOH.

It is known that in neutral water (pH 7) even 99% of boron is in the form of B-acid. In slightly alkaline water, certain anions of B acid happen. For example, at pH 8 water may contain 6% of H2BO3–.

The concentration of boron in natural water is regulated by two factors:

1) availability of this trace element in water-bearing rocks and soils;

2) geochemical conditions inside the aquifers. WHO has recommended a limit of 0.3 mg/l–1 boron. In studied waters the concentration of boron is in range between 2 and 385 ppb. Strong positive correlation as between B and Ca, Ti, Ge, Cl, HCO3

were determined.

Lithium

Lithium is probably common in amounts less than 1 ppm in water. The lithium Li+1 _{ion oxidation}

state is generally soluble and mobile in natural wa-ter (Reimann and Birke, 2010). Lithium in groundwater may have multiple geogenic sources. It occurs in the minerals spodumene (LiAlSi2O6)

and lepidolite (K2Li3Al4Si7O21(OH, F)3), but also in

many other minerals. Pegmatite and brines espe-cially are strongly enriched in Li (Kesler, et al,. 2012). In a European study, a median value of 2.6 µg/l Li (min. <0.2 µg/l and max. 75 µg/l) (Reimann and Birke, 2010). Concentrations of Li in studied waters are in range of 1.2–32.9 ppb.

Strontium

Strontium is very similar in chemical behavi-or to calcium and minbehavi-or amounts probably occur in many waters (Reimann and Birke, 2010). Concen-tration of Sr in studied waters is in range of 24– 2758 ppb.

Zinc

The maximum allowable concentration and permissible concentration of zinc in drinking water are 15 ppm and 5 ppm, respectively. According to WHO, the average values of zinc in all the water samples are below the permissible limit. The con-centration of zinc in all water samples is 2.24– 49.39 ppb. Hence all the samples collected from all sources are below from maximum permissible limit for zinc.

Nickel

The permissible concentration of nickel in ground water is 0.02 ppm. Concentrations of nickel in studied waters are in range of 0.33–2.26 ppb. All studied samples are within the permissible limit.

Beryllium and barium

Nothing is known of the distribution of beryl-lium in natural water. Barium has a highly

insolu-ble sulfate and only traces of barium can be ex-pected in waters where sulfate is present. Concen-trations of Ba in studied waters is in range of 0.19– 36 ppb.

Rubidium and cesium

Very little information is available about ru-bidium and cesium in natural water. Concentra-tions of Rb and Cs in studied waters vary from 0.11 to 15.75 and from 0.023 to 12.31 ppb, respec-tively.

Chromium

The maximum permissible limit of chromium in drinking water according to WHO is 0.05 ppm. The obtained data show that chromium content in investigated waters is within between 0.19 to 1.61 ppb.

Arsenic and selenium

Arsenic and selenium probably occur as ani-ons and are of interest because of their toxic char-acter, but rarely do unpolluted waters that are oth-erwise potable contain harmful amounts. Concen-tration of As is in range between 0.27 and 870.4 ppb, while the concentration of Se is 0.33–3.65 ppb.

T a b l e 3

Concentration of Co, Cr, V, As, Se, Sb, Tl, Bi, Ga, Ge and Pd

Co Cr V As Se Sb Tl Bi Ga Ge Pd

Trabotivište (Delčevo) 0.280 0.27 0.29 0.41 0.61 0.212 0.088 0.723 1.97 0.08 0.272

Istibanja (Kočani) 0.150 0.43 0.66 0.55 0.58 0.164 0.070 0.029 1.70 0.11 0.142

Neokazi – sample 1 (Probištip) 0.458 0.42 3.21 2.46 3.65 0.545 0.122 0.018 1.73 0.17 0.104 Neokazi – sample 2 (Probištip) 0.353 0.50 0.61 0.80 4.60 0.768 0.134 0.042 2.54 0.17 0.330

Gorni Balvan (Štip) 0.234 0.33 7.54 7.93 1.34 0.518 0.115 0.012 1.08 0.20 0.070

Plačkovica (Štip) 0.083 0.19 0.05 0.52 0.33 0.187 0.148 0.010 1.38 0.03 0.079

Karaorman (Štip) 0.195 2.22 0.78 0.35 1.59 0.056 0.090 0.014 0.48 0.25 0.100

Lakavica – sample 1 (Štip) 0.832 0.53 2.01 2.99 1.14 0.116 0.112 0.016 0.84 0.44 0.069 Lakavica – sample 2 (Štip) 0.849 0.64 2.38 2.31 1.64 0.081 0.108 0.015 0.99 0.45 0.122 Jargulica – sample 1 (Radoviš) 0.179 1.61 0.70 0.45 0.67 0.020 0.112 0.009 1.10 0.05 0.241 Jargulica – sample 2 (Radoviš) 0.186 0.44 0.35 0.34 2.93 0.042 0.086 0.010 2.36 0.06 0.056

Novo Selo (Strumica) 0.084 0.69 1.37 0.46 0.50 0.014 0.101 0.009 0.60 0.04 0.044

Murtino (Strumica) 0.118 0.28 0.06 117.8 0.41 0.063 0.081 0.009 2.91 0.10 0.072

Robovo (Strumica) 0.095 0.27 0.03 45.55 0.43 0.069 0.075 0.012 2.93 0.10 0.055

Gabrovo (Strumica) 0.107 0.26 0.39 0.37 0.41 0.080 0.084 0.023 0.24 0.04 0.057

T a b l e 4

Concentration of Ag,Sn,U, CaCO3, SO42-and Cl

Ag Sn U CaCO3 SO42- _Cl

Trabotivište (Delčevo) 0.187 0.143 1.781 360.5 45.78 13.93

Istibanja (Kočani) 0.012 0.018 2.051 228 83.90 32.14

Neokazi – sample 1 (Probištip) 0.025 0.041 8.377 345 218.4 64.3 Neokazi – sample 2 (Probištip) 2.112 0.044 9.468 336 131.3 105

Gorni Balvan (Štip) 0.038 0.015 0.297 285 101.17 40.71

Plačkovica (Štip) 0.006 0.021 0.001 58 13.71 7.5

Karaorman (Štip) 0.034 0.035 0.319 656 219.87 114.6

Lakavica – sample 1 (Štip) 0.014 0.031 4.995 592 449.3 60

Lakavica – sample 2 (Štip) 0.019 0.026 2.940 698 440.0 83.57

Jargulica – sample 1 (Radoviš) 0.039 0.022 0.123 142 30.16 32.14 Jargulica – sample 2 (Radoviš) 0.027 0.028 0.054 175 50.58 31.07

Novo Selo (Strumica) 0.007 0.028 0.301 105 6.04 16.43

Murtino (Strumica) 0.017 0.024 0.015 215 1.58 17.14

Robovo (Strumica) 0.004 0.032 0.022 235 26.32 25.71

Gabrovo (Strumica) 0.004 0.074 61.85 166 14.53 12.86

Smolare (Strumica) 0.004 0.014 0.065 75 33.31 18.21

Sulfate

Sulfate is the form in which sulfur usually oc-curs in water. Weathering of sulfide bearing rocks or direct solution of evaporate deposits may be im-portant sources of sulfate. The maximum value of sulfate in drinking water is 400 mg/liter (WHO, 2011).

Sulphate concentration in investigated waters is varies from 1.58. to 449.3 mg/l and these values are within permissible limits prescribed by WHO. The high concentration of sulfate in water from Lakavica might indicate the sulfate mineral in the aquifer of the system.

Chloride

Some chloride are dissolved from rocks and some may be associated with connate and juvenile water. Chloride in natural waters is derived from chloride-rich sedimentary rocks.

Chloride concentration varies from 7.5 to 114.6 mg/l which is lower than the WHO stan-dards.

Uranium

Traces of uranium are common in natural wa-ters. Uranium concentration in the study waters varies from 0.001 to 110.8 ppb.

Concentrations of NO3, NO2, PO43–, NH4, F,

HCO3 and pH are given in Table 5. Nitrate

Maximum concetnrations of nitrate were de-tected in waters from Neokazi (sample 2, 93.28 mg/l) and Karaorman (143.3 mg/l) and these val-ues are higher from the limits (50 mg/l) prescribed by WHO. Nitrate may be added to water by or-ganic pollution or leaching of fertilized soils. In some waters the presence of nitrate is not easily explained.

Fluoride

The main minerals of F are fluorspar (CaF2),

fluorapatite (3Ca3(PO4)·CaF2) and cryolite

(Na3AlF6). Fluorspar and fluorapatite are only

slightly soluble in water: at 20°C water dissolves only 14.7–22 mg/l of CaF2 (Крайнов et al., 2004).

Even such a poor solubility of these minerals de-pends upon the reaction of water-fluorspar is better soluble in alkaline water, although it is also slightly more soluble in acid water:

CaF2 + OH– = CaOH+ + 2F–,

CaF2 + 2H+ = Ca2+ + 2HF.

These minerals are also even less soluble in water rich in Ca.

Fluoride concentrations in water are normally very low. According to WHO 1984, the maximum permissible limit of fluoride in drinking water is 1.5 ppm and the highest desirable limit is 1.0 ppm. Fluoride concentrations above 1.5 ppm in drinking water cause dental fluorosis and much higher

con-centration skeletal fluorosis. Low concon-centration (approximately 0.5 ppm) provides protection against dental caries. Concentration of fluoride in the study area is in the range of acceptable limit 0.081–1.17 mg/l of WHO guidelines for drinking water quality (WHO, 2011).

T a b l e 5

Concentration of NO3, NO2, PO43–, NH4, F, HCO3 and pH

NO3 F PO43– _{NO2 NH4 HCO3 CO3 pH}

Trabotivište (Delčevo) 3.566 0.555 0.016 0.0083 0.098 278 301 7.09

Istibanja (Kočani) 11.95 0.455 0.030 0.0101 0.005 187 219 7.19

Neokazi – sample 1 (Probištip) 45.05 0.780 0.012 0.0006 0.005 261 285 7.71

Neokazi – sample 2 (Probištip) 93.28 0.928 0.012 0.0006 0.005 258 280 7.66

Gorni Balvan (Štip) 35.47 0.564 0.012 0.0006 0.005 235 249 8.2

Plačkovica (Štip) 0.147 0.081 0.017 0.0006 0.005 398 45 8.04

Karaorman (Štip) 143.3 0.872 0.012 0.0006 0.005 620 630 7.63

Lakavica – sample 1 (Štip) 1.864 0.472 0.012 0.0006 0.005 428 475 7.95

Lakavica – sample 2 (Štip) 21.65 0.266 0.015 0.0006 0.005 524 574 7.94

Jargulica - sample 1 (Radoviš) 34.38 0.136 0.013 0.0006 0.005 100 112 8.09

Jargulica – sample 2 (Radoviš) 12.72 0.154 0.013 0.0006 0.005 26 140 8.27

Novo Selo (Strumica) 1.86 0.374 0.067 0.0053 0.005 78 86 7.99

Murtino (Strumica) 0.813 0.373 0.083 0.0074 1.616 185 194 7.29

Robovo (Strumica) 0.536 0.254 0.019 0.0088 0.379 201 219 6.99

Gabrovo (Strumica) 0.416 1.17 0.011 0.0052 0.005 131 141 8.04

Smolare (Strumica) 0.715 0.317 0.012 0.0006 0.005 52 59 7.75

Ammonium ions

Maximum concetnrations of ammonium ions were detected in waters from Murtino (1.616 mg/l) and Gabrovo (0.379 mg/l) and these values are higher from limits prescribed by WHO.

Phosphate

Phosphate may be contributed by organic pol-lution and may be introduced in the treatment of public supplies, but is rarely present in amounts over 1 ppm. Concentration of phosphate in the study waters is in range of 0.012 – 0.315 ppm.

Bicarbonate is the major constituent of natural water. It comes from the action of water containing carbon dioxide on limestone, marble, chalk,

cite, dolomite, and other minerals containing cal-cium and magnesium carbonate. The carbonate-bicarbonate system in natural waters controls the pH and the natural buffer system. pH is an import-ant environmental factor which provides informa-tion on many types of geochemical balances (Shyamala et al., 2008). pH values of the study area are neutral to alkaline type in the range of ac-ceptable limit of 6.99–8.28, and they are in the de-sirable ranges, after WHO guidelines for drinking water quality (WHO, 2011).

According to the obtained values for total hardness, investigated waters are hard, moderately hard and very hard. High values for total hardness are mainly due to solubility of carbonate rocks.

The values for TH, TDS and EC are given in Table 6.

T a b l e 6

Concentration of TH, TDS and EC

Hardness concentracion CaCO3 (mg/l) (TH) Classification TDS EC (µS/cm)

Trabotivište (Delčevo) 216 very hard 770 1203

Istibanja (Kočani) 149 hard 656 1025

Neokazi – sample 1 (Probištip) 294 very hard 1046 1634

Neokazi – sample 2 (Probištip) 262 very hard 1041 1627

Gorni Balvan (Štip) 199 very hard 817 1277

Plačkovica (Štip) 45.6 soft 503 786

Karaorman (Štip) 486 very hard 2021 3158

Lakavica – sample 1 (Štip) 781 very hard 1747 2730

Lakavica – sample 2 (Štip) 748 very hard 2006 3134

Jargulica – sample 1 (Radoviš) 130 hard 388 606

Jargulica – sample 2 (Radoviš) 148 hard 450 703

Novo Selo (Strumica) 67.6 moderately hard 246 384

Murtino (Strumica) 89.3 moderately hard 469 733

Robovo (Strumica) 104 moderately hard 538 841

Gabrovo (Strumica) 77.5 moderately hard 364 569

Smolare (Strumica) 62.3 moderately hard 220 344

TDS

TDS is used for estimation of total dissolved salts in water (Purandara et al., 2003), which may have an impact on the taste and suitability for use of water for various purposes. The measured val-ues for TDS varies from 220 to 2021 ppm (avg. 830 ppm). On comparison with the WHO water standards (1000 ppm) was observed that 5 analy-zed samples (Neokazi – samples 1 and 2, К ara-orman, Lakavica – samples 1 and 2) have TDS concentrations greater than the prescribed limits.

EC

The electrical conductivity is a measure of the capacity of water to conduct electrical current, it is directly related to the concentration of salts dis-solved in water, and therefore to the Total Dis-solved Solids (TDS). Salts dissolve into positively charged ions and negatively charged ions, which conduct electricity. Never the less, when the salt concentration reaches a certain level, electrical conductivity is no longer directly related to salts concentration. This is because ion pairs are for-med. Ion pairs weaken each other's charge, so that above this level, higher TDS will not result in equally higher electrical conductivity.

CAI

Chloro-alkaline indices, CAI 1 = Cl– _{(Na + K)}

/ Cl and CAI 2 = Cl – (Na + K) / SO4 + HCO3 +

CO3 + NO3 (Schoeller, 1977), were calculated to

study the process of ion exchange between the na-tural water and its host environment during rock-water interaction. Positive CAI values noted in Neokazi (samples 1 and 2), Jargulica (samples 1 and 2), Novo Selo, Murtino, Robovo, Gabrovo and Smolare suggest that sodium and potassium from water are exchanged with calcium and magnesium in rock following base exchange reactions (chloro-alkaline equilibrium), where as negative CAI val-ues noted at Trabotivište, Istibanja, Karaorman Plačkovica, Lakavica (samples 1 and 2), suggest that magnesium and calcium from water are ex-changed with sodium and potassium in rock fa-vouring cation-anion exchange reactions (chloro-alkaline disequilibrium). a) natural water Na , K_2–" + 2-Ca , Mg

⎯⎯⎯⎯→

←⎯⎯⎯⎯

country rock b) natural water Ca2+"₊, Mg₊2+ Na , K

⎯⎯⎯⎯⎯

→

←⎯⎯⎯⎯

⎯

country rock One method of comparing the results of chemical analyses of natural water is with at

rili-near diagram (Piper, 1953) (Fig. 2). This diagram consists of two lower triangles that show the per-centage distribution, on the milli equivalent basis, of the major cations (Mg++_{, Ca}++ _{and Na}+ _{+ K}+_{) and}

the major anions (Cl–_{, SO}

42– and CO32– + HCO3–)

and a diamond-shaped part above that summarizes the dominant cations and anions to indicate the final water type. This classification system shows the anion and cation facies in terms of major-ion percentages. The water types are designated ac-cording to the area in which they occur on the dia-gram segments.

The cation distribution indicates that the sam-ples range in composition from calcium / magne-sium to predominantly mixed cation. In the anion triangle, there is a tendency toward bicarbonate type water.

The high concentration of calcium and mag-nesium might because for hard water in some of the investigated samples.

The correlation matrix using the raw data ana-lysis shows a strong positive correlation between Ca → SO4, Na, Mg; Ti → Ca, Mg, Na, K, B; U →

Mo, Rb, Cs, As; B → Ca, Ti, Ge, Cl, HCO3; Li →

Mg, Na, K, B, Sr, Rb; Ge → Ca, Mg, Na, B, Ti, Li,

Cl, Pb; Cl → Mg, Na, K, B, Sr, Li, Pb; HCO3 →

Ca, Mg, Na, K, B, Ti, Sr, Li, Pb, Co, Se, Ge; NO3

→ Na, Sr, Li, Pb, Cs, Se. Аlso significant positive correlation between SO4–Na, TDS – EC. The rest

of other correlations between ions are not signi-ficant.

Fig. 2. Piper diagram of investigated waters

CONCLUSION This study showed that most of the analyzed

elements in all selected water samples were below the Macedonian maximum allowable levels and WHO water standards. In creased concentrations of some elements indicate anthropogenic pollution of the water from the fertilization of arable land, livestock farms. There is a strong positive correla-tion between Ca → SO4, Na, Mg; Ti → Ca, Mg,

Na, K, B; U → Mo, Rb, Cs, As; B → Ca, Ti, Ge, Cl, HCO3; Li → Mg, Na, K, B, Sr, Rb; Ge → Ca,

Mg, Na, B, Ti, Li, Cl, Pb; Cl → Mg, Na, K, B, Sr, Li, Pb; HCO3 → Ca, Mg, Na, K, B, Ti, Sr, Li, Pb,

Co, Se, Ge; NO3 → Na, Sr, Li, Pb, Cs, Se;

SO4 → Na, TDS → EC.

According to the obtained values for total hardness investigated waters are hard, moderately hard and very hard. High values for total hardness

are mainly due to solubility of carbonate rocks. Positive CAI values noted in Neokazi (samples 1 and 2), Jargulica (samples 1 and 2), Novo Selo, Murtino, Robovo, Gabrovo and Smolare suggest that sodium and potassium from water are ex-changed with magnesium and calcium in rocks following base exchange reactions (chloro-alkaline equilibrium), whereas negative CAI (Chloro-Alka-line Indices) noted at Trabotivište, Istibanja, Karaorman Plačkovica, Lakavica (samples 1 and 2) suggest that magnesium and calcium from water are exchanged with sodium and potassium in rocks favouring cation-anion exchange reactions (chloro-alkaline disequilibrium). After Piper diagram the type of water in the study area is mainly calcium / magnesium bicarbonate.

REFFERENCES

[1] Edwards, K. J., Bond, P. L., Druschel, G. K., Mcguire, M. M., Hamers, R. J. & Banfield, J. F.: Geochemical and biological aspects of sulfide mineral dissolution: lessons from Iron Mountain, California. Chemical Geology, 169, 383–397 (2000).

[2] Hem, J. D.: Study and Interpretation of the Chemical Characteristics of Natural Water, 3d ed: U.S. Geological Survey Water – Supply Paper, 2254–263 p. (1989). [3] Kesler, S. E.; Gruber, P. W.; Medina, P. A.; Keoleian, G.

re-sources: Relative importance of pegmatite, brine and other deposits. Ore Geol. Rev. 48, 55–69 (2012).

[4] КрайновС. Р., РыженкоБ. Н., ШвецВ. М.: Геохимия подземныхвод. Москва: Наука. 2004, 667 c.

[5] Selinus, O. et al., Ed.: Essentials of Medical Geology – Impacts of the Natural Environment on Public Health, Burlington, MA:Elsevier Academic Press, 2005. 812 pp. ISBN: 0-1263-6341-2, $99.95 cloth

[6] Piper, A. M.: A graphic procedure in the geochemical interpretation of water analyses. U.S. Geol. Survey Ground water Note 12 (1953).

[7] Purandara, B. K., Varadarajan, N., Jayashree, K.: Impact of sewage on ground water quality – case study. Pollut. Res. 22 (2):189 (2003).

[8] Pyenson, B.: Effects of Nitrate Fertilization on Pyrite Oxidation in Salt Marsh Sediments, 2002.

[9] Reimann, C.; Birke, M.: Geochemistry of European Bot-tled Water; Borntraeger Science Publishers, Stuttgart, Germany, 2010.

[10] Schoeller, H.: Geochemistry of groundwater. In: Ground-water studies. – An International Guide for Research and Practice. UNESCO, Paris, 1977, Ch. 15, pp. 1–18. [11] Shyamala, R., Shanthi, M. and Lalitha, P.:

Physicochemi-cal analysis of borewell water samples of Telungupa-layam area in Coimbatore District, Tamilnadu, India. E-Journal of Chemistry, Vol. 5, No. 4, pp. 924–929 (2008). [12] Williamson, M. A. & Rimstidt, J. D.: The kinetics and

electrochemical rate-determining step of aqueous pyrite oxidation. Geochimica et Cosmochimica Acta, 58, 5443– 5454 (1994).

[13] World Health Organization 1984, Guidelines for drink-ing-water quality.

[14] World Health Organization 2011, Guidelines for drink-ing-water quality, 4th edition.

Резиме ГЕОХЕМИСКАПРОЦЕНАНАНЕКОИПРИРОДНИВОДИ ОДИСТОЧНАИЈУГОИСТОЧНАМАКЕДОНИЈА Тена Шијакова-Иванова1_{, Весна Амбаркова}2 1_{Факултетзаприродниитехничкинауки, Универзитет „ГоцеДелчев“,} п. фах 201, МК-2001, Штип, РепубликаМакедонија, 2_{Факултетзастоматологија, Катедразапревентивнаипедијатрискастоматологија,} Универзитет„Св. КирилиМетодиј“ воСкопје, Водњанска 17, Скопје, РепубликаМакедонија tena.ivanova@ugd.edu.mk Клучни зборови:природниводи; елементивотреги; pH; TDS Воовојтрудедаденагеохемискапроценананекои природни води од источна и југоиситочна Македонија. Анализирани се 16 примероци вода од селата Тработи -виште, Истибања, Неокази (двапримерока ), ГорниБал -ван, Плачковица, Караорман ,Лакавица (два примерока), Јаргулица (двапримерока), НовоСело, Муртино, Робово, ГабровоиСмоларе. Добиенитеподатоципокажаадекапо -големделодиспитуваните елементисе вограниците на максимално дозволените концентрации пропишани од Светската здравствена организација. Зголементите кон -центрациинанекоиоделементитесерезултатодантропо -генозагадувањенаводатапрекуѓубрењетонанивитеиод сточарскитефарми. Позитивнакорелацијапостоипомеѓу:

Ca → SO4, Na, Mg; Ti → Ca, Mg, Na, K, B; U → Mo, Rb, Cs, As; B → Ca, Ti, Ge, Cl, HCO3; Li → Mg, Na, K, B, Sr, Rb; Ge → Ca, Mg, Na, B, Ti, Li, Cl, Pb; Cl → Mg, Na, K, B, Sr, Li, Pb; HCO3→ Ca, Mg, Na, K, B, Ti, Sr, Li, Pb, Co, Se, Ge; NO3 → Na, Sr, Li, Pb, Cs, Se; SO4 → Na, TDS → EC.

Спореддобиенитевредностизатврдостанаводата, испи -туванитеводисетврди, умеренотврдиимногутврдисо исклучок на водата од Плачковица која е мека. Високи вредностизатврдостанаводатаседолжатглавнонарас -творливостанакарбонатнитекарпи. Спореддијаграмотна Piper испитуванитеводисеглавнокалциум/магнезиумби -карбонатни.